Smee Donald F, Sidwell Robert W, Kefauver Debbie, Bray Mike, Huggins John W
Institute for Antiviral Research, Utah State University, Logan, Utah 84322-5600, USA.
Antimicrob Agents Chemother. 2002 May;46(5):1329-35. doi: 10.1128/AAC.46.5.1329-1335.2002.
Cidofovir ([(S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine] [HPMPC])-resistant forms of camelpox, cowpox, monkeypox, and vaccinia viruses were developed by prolonged passage in Vero 76 cells in the presence of drug. Eight- to 27-fold-higher concentrations of cidofovir were required to inhibit the resistant viruses than were needed to inhibit the wild-type (WT) viruses. Resistant viruses were characterized by determining their cross-resistance to other antiviral compounds, examining their different replication abilities in two cell lines, studying the biochemical basis of their drug resistance, and assessing the degrees of their virulence in mice. These viruses were cross resistant to cyclic HPMPC and, with the exception of vaccinia virus, to (S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)adenine. Three of the four resistant cowpox and monkeypox viruses exhibited reduced abilities to infect and replicate in 3T3 cells compared to their abilities in Vero 76 cells. Compared to the WT virus polymers the resistant cowpox virus DNA polymerase was 8.5-fold less sensitive to inhibition by cidofovir diphosphate, the active form of the drug. Intracellular phosphorylation of [3H]cidofovir was not stimulated or inhibited by infection with resistant cowpox virus. In intranasally infected BALB/c mice, WT cowpox virus was 80-fold more virulent than the resistant virus. Cidofovir treatment (100 mg/kg of body weight, given one time only as early as 5 min after virus challenge) of a resistant cowpox virus infection could not protect mice from mortality. However, the drug prevented mortality in 80 to 100% of the mice treated with a single 100-mg/kg dose at 1, 2, 3, or 4 days after WT virus challenge. By application of these results to human orthopoxvirus infections, it is anticipated that resistant viruses may be untreatable with cidofovir but their virulence may be attenuated. Studies will need to be conducted with cidofovir-resistant monkeypox virus in monkeys to further support these hypotheses.
通过在药物存在的情况下在Vero 76细胞中长时间传代，获得了对西多福韦（[(S)-1-(3-羟基-2-膦酰甲氧基丙基)胞嘧啶][HPMPC]）耐药的骆驼痘病毒、牛痘病毒、猴痘病毒和痘苗病毒毒株。抑制耐药病毒所需的西多福韦浓度比抑制野生型（WT）病毒所需的浓度高8至27倍。通过确定耐药病毒对其他抗病毒化合物的交叉耐药性、检测它们在两种细胞系中的不同复制能力、研究其耐药性的生化基础以及评估它们在小鼠中的毒力程度，对耐药病毒进行了特性分析。这些病毒对环状HPMPC具有交叉耐药性，并且除痘苗病毒外，对(S)-1-(3-羟基-2-膦酰甲氧基丙基)腺嘌呤也具有交叉耐药性。与在Vero 76细胞中的感染和复制能力相比，四种耐药牛痘病毒和猴痘病毒中的三种在3T3细胞中的感染和复制能力有所降低。与野生型病毒聚合酶相比，耐药牛痘病毒DNA聚合酶对药物的活性形式二磷酸西多福韦抑制的敏感性低8.5倍。耐药牛痘病毒感染不会刺激或抑制[3H]西多福韦的细胞内磷酸化。在经鼻感染的BALB/c小鼠中，野生型牛痘病毒的毒力比耐药病毒高80倍。用西多福韦治疗（100 mg/kg体重，仅在病毒攻击后5分钟尽早给药一次）耐药牛痘病毒感染不能保护小鼠免于死亡。然而，在野生型病毒攻击后1、2、3或4天，单次给予100 mg/kg剂量的药物可使80%至100%的小鼠免于死亡。将这些结果应用于人类正痘病毒感染，预计耐药病毒可能无法用西多福韦治疗，但其毒力可能会减弱。需要用对西多福韦耐药的猴痘病毒在猴子身上进行研究，以进一步支持这些假设。
